Sea Technology:Halmatic Building World's Tallest Yacht Mast

January 13, 2003

295-ft. (89.9-m) Mast to support 2,900 sq. m. of Sail

Halmatic is manufacturing a 295-ft. (90-m) mast that will be fitted on the world's biggest sloop, currently under construction by its parent Vosper Thornycroft Shipbuilding, part of the VT Group. Mirabella V will be around 246 ft. (75 m) long and its mast will support some 2,900 sq. m. of sail. Halmatic will use its long-standing expertise in composite manufacture to produce the hollow carbon epoxy mast, which will have a maximum cross section of 1.5 m and structural thickness of up to 32 mm.

The mast is manufactured in halves, with one comprising a complete length and the other divided into three sections. Framework for the mold will be made from MDF cut on VT's advanced laser cutting and profiling machine. The manufacturing process, a similar method to that used in the production of Grand Prix racing cars and the aerospace industry, will consist of layers of cloth pre impregnated with resin made pliable and laid on top of each other. A vacuum bag will be used to create the required pressure every few layers. Structural expertise will be provided by Hamble-based High Modulus, who are involved in composite engineering aspects for the total Mirabella project.

At regular intervals during the build the mast will be cured using a heat process with temperatures up to 70 degrees C. Carbon compression tubes will be pre-fitted to coincide with the position of each spreader. It is estimated that some five tons of cabling will be fitted within the hollow centre of the mast, including a mass of sensors to monitor the sail performance. Finally, the sections of the mast will be glued together using an epoxy adhesive before the mast is stepped following the Mirabella V's launch in May 2003.

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